Overload circuit breaker



Jan. 24, 1939.

w. 'REXFORD OVERLOAD CIRCUIT BREAKER Filed Dec. 10, 1955 Willis Rexford ATTORNEYS Patented Jan. 24, 1939 PATENT OFFICE OVERLOAD CIRCUIT BREAKER Willis Rexford, Girard, Pm, assignor to' Louis Marx 8; Company, Inc., New York, N. Y., a cornotation of New York ApplicationDecember 10, 1935, Serial No. 53,701 10 Claims. (01. 200-111) This invention relates to circuit breakers, and more particularly to an overload circuit breaker for low voltage circuits, particularly electrically operated toys, for example toy railroads.

The object of the present invention is to generally improve circuit breakers of this character. More particular objects are to insure abrupt instantaneous wide opening of the contacts when the circuit breaker is tripped; to greatly simplify the necessary structure'and thereby lessen its manufacturing cost; to insure sensitive response; to make the sensitivity adjustable; and to provide restoring mechanism which is simple, effective and dependable.

15 To the accomplishment of the foregoing and other objects which will hereinafter appear, my invention consists in the circuit breaker elements and their relation one to the other as hereinafter are more particularly described in the specification and sought to be defined in the claims.

The specification is accompanied by a drawing in which:

Fig. 1 is a section taken in elevation through a circuit breaker embodying features of my in- 25 vention;

Fig. 2 is a transverse section taken in elevation in the plane of the line 2-2 of Fig. 1;

Fig. 3 is a horizontal section taken in the plane of the line 3-3 of Fig. 1;

Fig. 4 is an enlarged section through the operating mechanism and is taken in the plane of the line 4-4 of Fig. 2;

Fig. 5 is a wiring diagram for the circuit breaker; and

Fig. 6 is a schematic diagram of a modification and is explanatory of the invention.

Referring to the drawing, and more particularly to Fig. 5, the circuit breaker is conventional in comprising a low impedance coil l2 and 40 a pair of relatively movable contacts l4 and I6 which are connected in series with a main or load current, the coil I2 being associated with mechanism adapted to open or separate the contacts l4 and I6 when the current flowing through the coil is excessive. In the present case the circuit breaker is used in connection with an electrically operated toy railroad, a fragment of the track of which is shown at l8. The railroad is energized by a suitable step-down transformer 20, the pri- 50 mary 22 of which is connected to an ordinary household lighting circuit, while the secondary 24 is connected at one end to a third rail 26 and at the other end to the grounded or wheelbearing rails 28. The circuit breaker is provided 55 with binding posts 30 which are connected in series with either leg of the wiring between the transformer secondary 24 and the track I. If desired, a warning signal lamp 32 may be connected in parallel with the circuit breaker, that is, between the binding posts 30 as shown, the 5 said lamp being extinguishedwhen contacts l4 and I6 are closed because the resistance of coil I2 is negligible compared with the resistance of the lamp. Upon overload or short-circuit, however, when contacts and I6 are separated, the 10 lamp 32 is energized thus indicating the existence of a short-circuit which should be investigated and eliminated.

Referring now to Figs. 1 through 4 of the drawing, the circuit breaker mechanism is mounted on a frame comprising a piece of sheet metal bent to U-shaped section and thus forming side walls 34 and a front wall 36. The frame is completed by a separate plate or back wall 38. Contact I4 is here shown as a stationary contact and is insulatedly mounted at the upper end of front plate 36. As is best shown in Fig. 4, the

outer end of the contact is passed through insulntion washers 40 and is riveted at 42 over a connection lug 44. The mating contact I6 is mov- 2e able, and for this purpose is mounted at the upper end of a lever or vane 46 which is pivoted at 48. For simplicity the desired pivotal relation is obtained by forming V-shaped notches or openings 50 in the upper ends of side plates 34, and vane 46 is made greater in width than the distance between the side plates and is disposed with its lower edge in the V-shaped openings. Contact i6 is insulated with respect to the main frame or structure and this is most-readily accomplished by making vane 46 of a slab of insulation such as fibre board, synthetic resinous material or the like. The contact is secured to slab 46 by riveting the same in place at 52 (see Fig. 4), a suitable connection lug 54 being disposed behind the rivet head.

To obtain rapid opening of contacts l4 and i 6 the vane is placed in'unstable equilibrium by resilient means 56, the force of which is exerted generally in the direction of vane 46 and toward '45 fulcrum 48. Contacts l4 and iii are closed when the vane is on one side of dead center and are abruptly opened when the vane is moved to the other side of dead center.

This result is accomplished by means of a solenoid l2 which influences an axially reciprocable core 60. The lowerend of resilient means 56 is connected to core 60 and the parts are so proportioned that when the solenoid is sufllciently energized, the core is shifted from the solid to the dotted line position shown in Fig. 4, thereby shifting the line of force of resilient means 56 to the broken line position 62 which, it will be noted,

falls outside the fulcrum 46, thereby tripping the vane 46 past dead center. Because of the in.- fiuence of resilient means 56, the vane is abruptly tripped to the fully opened position shown in broken lines in Fig. 4. The limiting position when open is readily determined by the walls of V-shaped opening 56. The limiting position when closed is of course determined by meeting of contacts I4 and i6, and is preferably such that the vane is .beyond dead center and in stable condition but only slightly beyond dead center so that it is readily tripped.

In order to take the reaction of resilient means 56 and in order to assist operation of solenoid l2, and most importantly, in order to obtain an exceedingly sudden opening of contacts l4 and I6, thereby minimizing arcing at the contacts, I find it desirable to place the lower end also in unstable equilibrium. To this end I provide a second pivoted lever or vane 64 which as here illustrated is generally in alignment with the primary vane or lever 46 but is pointed in opposite direction. The side walls 34 of the frame are cut away at the lower end to form notched openings 66 which receive the upper or inner edge of vane 64. This vane may be and preferably is made of metal. Its lower or outer edge is recessed at 68 (Fig. 2) to receive the solenoid core 60. The end of the core is preferably provided with a thin sheet metal washer 10 (Fig. 4) held in place by riveting or upsetting the end of the core, as shown at 12. The forward limiting position of secondary lever 64 and core 60 is determined by a stop I4 which is preferably adjustable as by using a screw 16 threadedly received in the front wall 36 of the frame and locked in adjusted position by a suitable lock nut 18. Secondary lever 64 is itself placed in unstable equilibrium at dead center by the use of a secondary resilient means 80 which in the present case is the lower end of the same pull spring which acts as the primary resilient means 66 for primary lever 46.

It will be understood that the forward limiting position of vane 64 is at one side of dead center and that solenoid I2 when overloaded draws vane I 64 to and slightly beyond dead center, whereupon it is abruptly pulled all the way over to the broken line position shown in Fig. 4 by secondary resilient means 80, at which time the line of connection 62 between secondary and primary vanes falls beyond fulcrum 48, thereby moving vane 46 beyond dead center, the movement of vane 46 then being completed by means of the primary resilient means 56. It is necessary to understand that in the present embodiment of the invention, a single. pull spring 56 fulfills three entirely separate and independent functions: it acts as a trip spring for the upper or primary vane 46; it also acts as a trip spring for the lower or secondary vane 64; it further acts as a connecting link between the two vanes, for which last-named function it would not be essential to use resilient means. These three functions will be'made clear by reference to Fig. 6 which schematically illustrates a modified form of the invention in which separate trip springs and connecting link are employed. For clarity the springs have been changed from pull springs to push springs.

Referring to Fig. 6, it will be seen that movable contact I6 is mounted on a primary lever 46 pivoted at 48 and that the solenoid core 60 is connected to a secondary lever .64 pivoted at 66 much as previously described. In the present case. however, primary lever 46 has associated with it a separate resilient means 86, while secondary lever 64 has associated with it secondary resilient means 82. Levers 46 and 64 are connected by a suitable link 84. The springs and 82 are shown as push springs, but could of course be separate pull springs anchored between pivots 46 and 66. When solenoid coil I2 is overloaded it attracts core 60 thereby moving lever 64 beyond dead center, whereuponit is quickly tripped by spring 62 to the dotted line position 64' at which time the link 84' lies outside of pivot 48 and consequently moves primary-lever 46 to and beyond dead center. The preliminary opening of the contacts is abrupt because of the suddenness with which the movement of secondary lever 64 is completed,

and the full or wide opening of the contacts is ensured by the primary trip spring 80.

In the preferred form of the invention shown in Figs. 1 through 4, the functions of trip springs 86) and 82 and of connecting link 64 are all combined in a single pull spring, the upper and lower ends of which may be thought of as separate trip springs, while the entire spring acts as a connecting link between the primary and secondary.

levers. Of course, these functions may be separated even when using pull springs, and conversely, may be combined when using a push spring, as for example, by inverting the levers shown in Fig. 6 to place the pivots at the outer ends, and disposing a single compression spring between the movable inner ends, the levers then preferably being disposed on opposite sides of dead center rather than on a common side of dead center.

Reverting now to Figs. '1 through 4, the common pull spring is preferably made in duplicate, one spring being disposed on 'eachside of the frame. The vanes 46 and 64 are provided with outwardly projecting arms 90 at their outermost ends over. which the pull springs are hooked. The arrangement is thus made symmetrical, and there is no interference with transverse or bodily movement of the springs from one side to the other of dead center, for the vanes and fulcrum points thereof are disposed entirely between the springs. The springs incidentally operate to hold the vanes on their fulcrum seats and thus function to hold movable parts in assembled relation. To restore the parts to closed circuit condition after the circuit breaker has been tripped, I provide a manually operable plunger 92 which is T-shaped as is best shown in Fig. 3, the inner end being provided with a pair of sidewardly extending arms 94. These pass through appropriate guide slots 96 in the side walls of the frame. The ends of arms 94 are disposed at the sides of the springs 56, 811, and it will be evident that by pushing plunger 92 forwardly. the springs are moved bodily forwardly and carry the upper and lower vanes past dead center to the stable initial or closed circuit position. The slots 96 in the side walls of the frame are preferably carried forwardly a sufficient distance so that plunger}! can actually bend the springs forwardly a substantial distance further than the limiting positions of the vanes, thus insuring movement beyond dead center. When the circuit breaker is tripped or opened, the resulting transverse or bodily movement of the springs causes the plunger to be moved outwardly and this may itself be used as an indication that the circuit breaker has been tripped.

However, as a further indication, the lamp 82 previously referred to may be employed. this lamp preferably being received in a socket 08 mounted atthe center of a top wall I of the circuit breaker casing. Lamp 32 is preferably surrounded by a housing I02 having transparent windows I 04. The neck I06 of housing I02 may be provided with outwardly extending arms I08 slidably received beneath retained lugs H0. The

housing may be oscillated to free arms I08 and then removed for replacement of the lamp should it become burned out.

The circuit breaker mechanism is housed within a square upright casing comprising a side II2 made of a single piece of sheet metal, the meeting edges of which are connected by suitable tongue and slot joints II4 (Fig. 3). Side wall II2'is secured to an appropriate base I I6 by suitable tongue and slot connections II8 (Fig. 2) and the top wall I00 is similarly secured to the side wall I I2 by tongue and slot connections or equivalent construction.

The circuit breaker frame is secured to one face of side wall I I2 preferably by using tongue and slot connections I20 (Figs. 1 and 3), the tongues preferably passing through slots in the back wall 38 of the frame and thence through the housing wall after which they are bent sidewardly. The back wall 38 of the frame is not essential but it is preferred to use the same in order to mount solenoid I2 thereon. As will be seen by reference toFig. 1, the lower end of back wall 38 is displaced inwardly slightly as shown at I22, and the rear end of the solenoid spool is passed through wall I22 and riveted in place. With this construction the circuit breaker mech: anism is a complete unit removable from the housing and it is thus readily possible to mount the circuit breaker in any desired form of housing and in any desired position. It should be understood that the circuit breaker may be disposed horizontally instead of vertically, for example, in which case plunger 92 will project vertically from the top of the casing and may itself be used as the sole "warning signal to indicate that the circuit breaker has opened.

Binding posts are mounted on base HE, and the manner in which. the wiring within the unit duplicates the arrangement shown in Fig. 5, will be clear from examination of the drawing, the lamp 32 being connected by relatively light flexible leads I24 tobinding posts 30; one end of solenoid I2 being connected to one of the binding posts '30 by a lead I26; the other end of solenoid I2 being connected to stationary contact I4 by a lead I28; and movable contact I6 being connected to the other binding post by a lead I30.

It is believed that the mode of constructing and using, as well as the operation and many advantages of. my improved overload circuit breaker, will be apparent from the foregoing detailed descriptlon'thereof. It will also be apparent that while I have shown and described the invention in a preferred form, many changes and modifications may be made in the structure disclosed,

without departing from the spirit of the invention defined in the following claims.

I claim: I

1. An overload circuit breaker comprising a stationary contact, a movable contact mounted on a pivoted lever, a pull spring having one end connected to said lever and exerting a force in a direction along the lever toward the pivot thereof thereby placing the lever in unstable equilibrium, and means including a series-connected solenoid having a core movable for a substantial distance in a direction transverse of the lever and spring, said core being located at and connected to the other end of said pull spring for moving the other end of said spring from a position where its line of force lies along one side of the pivot to a new position where its line of force falls on the other side of the pivot, whereby the movable contact is abruptly moved from closed to open position, and manually operable means bearing against said spring at an intermediate point for restoring the parts to initial position.

2. A circuit breaker comprising a stationary contact, a movable contact mounted on a pivoted lever, a pull spring connected to said lever and exerting a force directed generally in the direction of the lever toward the pivot in order to place the lever in unstable equilibrium, means including a solenoid core movable for a substantial distance in a direction transverse of the lever and spring, said core being located at and connected to the other end of said pull spring and being operated by a solenoid for shifting the other end of said pull spring transversely of the lever to either side of dead center, said means itself including a pivoted lever pointed in generally opposite direction and itself placed in unstable equilibrium by the aforesaid pull spring, and manually operable restoring means including a member movable against said pull spring to restore the parts to the normal or closed circuit position.

3. An overload circuit breaker for electrically operated toys or like low voltage circuits, said circuit breaker comprising a stationary contact, a movable contact mounted on a pivoted lever, a secondary pivoted lever approximately in alignment with the primary lever, resilient means interconnecting said pivoted levers and-normally urging the same toward the fulcrums thereof and thereby placing the same in unstable equilibrium at dead center, a series-connected solenoid having a movable core connected to said secondary lever but not connected to said primary lever, the parts being so arranged that when the solenoid moves the seondary lever from normal position past dead center to overload position the aforesaid resilient means abruptly moves the primary lever past dead center thereby changing the contact from closed to open position, stop means to determine the normal position of the secondary lever in order to control the sensitivity'of the circuit breaker, and manually operable means bearing against said pull spring to restore the parts to initial position,

4. An overload circuit breaker for electrically operated toys or like low voltage circuits, said circuit breaker comprising a stationary contact, a movable contact mounted on a pivoted lever, a

seondary pivoted lever approximately in alignment with the primary pivoted lever but pointed in opposite direction with the pivots toward one another, a pull spring interconnecting said pivoted levers and normally urging the same toward the fulcrums thereof and thereby placing the same in unstable equilibrium, a serles-connected solenoid having a movable core connected to said secondary lever but not connected to said primary lever, the parts being so arranged that when the solenoid moves the secondary lever past dead center the aforesaid pullspring abruptly moves the primary lever past dead center thereby changing the contact from closed to open Dusition, and manually operable means bearing against said pull spring to restore the parts to initial position.

5. An overload circuit breaker for electrically operatedtoys or like low voltage circuits, said circuit breaker comprising a stationary contact, a movable contact mounted on a pivoted lever,

a secondarypivoted lever approximately in alignment with the primary pivoted lever but pointed in opposite direction, resilient means interconnecting said pivoted levers and normally urging the same toward the fulcrums thereof and thereby placing the same in unstable equilibrium at dead center, a series-connected solenoid having a movable core connected to said secondary lever but not connected to said primary lever, the parts being so arranged that when the solenoid moves the secondary lever past dead center the aforesaid resilient means abruptly moves the primary lever past. dead center thereby changing the contact from closed to open position, and means to adjust the sensitivity of the circuit breaker by determining the limiting position of the secondary lever.

6. A circuit breaker comprising spaced frame plates having oppositely directed V-shaped openings at opposite ends thereof, a flat vane of insulation material disposed in one of said openings and oscillatable therein, a stationary contact on the frame, a movable contact on said vane, a secondary vane disposed at the opposite end of the frame and oscillatable in the opening at that end, a pair of pull springs extending between the outer ends of the vanes at opposite sides of the frame, a solenoid .having a movable core connected to the secondary vane and adapted to move the same from a position at one side of dead center to a position at the opposite side of dead center, the latter limiting position being such that the line of force of the aforesaid springs falls beyond the fulcrum point of the primary vane, whereupon said primary vane is very abruptly pulled from a position at one side of dead center to a position on the other side of dead center in order to open the aforesaid contacts, said pull springs being the sole means for moving said primary vane from closed circuit position to open circuit position.

'7. A circuit breaker comprising spaced frame plates having oppositely directed. 'V-shaped openings at opposite ends thereof, a flat vane of insulation material disposed in one of said openings and oscillatable therein, a stationary con tact on the frame, a movable contact on said vane, a secondary vane disposed at the opposite end of the frame and oscillatable in the opening at that end, a pair of pull springs extending between the outer ends of the vanes atopposite sides of the frame, a solenoid having a movable core connected to the secondary vane and adapted to move the same from a position at one side of dead center to a position at the opposite side of dead center, the latter limiting position being such that the line of force of the aforesaid springs falls beyond the fulcrum point of the primary vane, whereupon said primary vane is very abruptly pulled from a position at one side of dead center to a position on the other side of dead center in order to open the aforesaid contacts, said pull springs being the sole means for moving said primary vane from closed circuit position to open circuit position, and restoring means to restore the circuit breaker to closed condition, said restoring means including a member movable against the aforesaid springs to move both primary and secondary vanes to one side of dead center.

8. A circuit breaker comprising spaced frame plates having oppositely directed V-shaped openings at opposite ends thereof, a flat vane of insulation material disposed in one of said openings and oscillatable therein, a stationary contact on the frame, a movable contact on said vane, a secondary vane disposed at the opposite end of the frame and oscillatable in the opening at that end, a pair of pull springs extending between the outer ends of the vanes at opposite sides of the frame, a solenoid having a movable core connected to the secondary vane and adapted to move the same from a position at one side of dead center to a position at the opposite side of dead center, the latter limiting position being such that the line of force of the aforesaid springs falls beyond the fulcrum point of the primary vane, whereupon said primary vane is very abruptly pulled from a position at one side of dead center to a position on the other side of dead center in order to open the aforesaid contacts, said pull springs being the sole means for moving said primary vane from closed circuit position to open circuit position, and means to adjust the sensitivity of the circuit breaker by determining a limiting position of the secondary vane.

9. A circuit breaker comprising spaced frame plates having oppositely directed V-shaped openings at opposite ends thereof, aflat vane of in sulation material disposed in one of said openings and oscillatable therein, a stationary contact on the frame, a movable contact on said vane, a secondary vane disposed at the opposite end of the frame and oscillatable in the opening at that end, a pair of pull springs extending between the outer ends of the vanes at opposite sides of the frame, a solenoid having a movable core connected to the secondary vane and adapted to move the same from a position at one side of dead center to a position at the opposite side of dead center, the latter limiting position being such that the line of force of the aforesaid springs falls beyond the fulcrum point of the primary vane, whereupon said 'primaryvane is very abruptly pulled from a position at one side of dead center to a position on the other side of dead center in order to open the aforesaid contacts, said pull springs being the sole means for moving said primary vane from closed cir cuit position to open circuit position, restoring means to restore the circuit breaker to closed condition, said restoring means including a member movable against the aforesaid springs intermediate their ends, to move both primary and secondary vanes to the closed side of dead center,

and adjusting means to determine the sensitivity of the circuit breaker.

10. A circuit breaker comprising spaced frame plates having oppositely directed V-shaped openings at opposite ends thereof, a flat vane of insulation material disposed in one of said openings and oscillatable therein, a stationary contact on the frame, a movable contact on said vane, a secondary vane disposed at the opposite end of the frame and oscillatable in the opening at that end, a pair of pull springs extending between the outer ends of the vanes at opposite sides of the frame, a solenoid having a movable core connected to the secondary vane and adapted to move the same from a position at one side of dead center to a position at the opposite side of dead center, the latter limiting position being such that the line of force of the aforesaid springs falls beyond the fulcrum point of the m ca": 5

primary vane, whereupon said primary vane is very abruptly pulled from 'a position at one side of dead center to a position on the other side of dead center, in order to. open the aforesaid contacts, said pull springs being the sole means formoving said primary vane from closed circuit position to open circuit position, restoring means to restore the circuit breaker'to closed condition, said restoring means including amember movable against the aforesaid springs to move both primary and secondary vanes to the closed side oi. dead center. and adjusting means to determine the sensitivity of the circuit breaker, said adjusting means including a screw determining the limiting position oi the secondary vane on the closed aide oi dead center.

WILLIS REXI'ORD. 

